Michael Tackett/CBS

Summertime used to be a TV wasteland. For decades, a viewer’s options were limited to reruns of shows they’d already watched during the regular fall-to-spring season, junk series deemed not good enough by networks to air on the fall schedule, and mind-numbing reality shows.

Not only are we now seeing a rise in new shows airing during the summer, the shows are actually good, too. A lot of folks are celebrating this change. TV writers, however, are likely not.

While viewers may have groaned at the tradition of rerunning old episodes of TV series during the summer, TV writers used to count on it. When a network-TV show is repeated, the writer who is credited with penning the episode receives a residual payment, defined by Writers Guild of America (PDF) as “compensation paid for the reuse of a credited writer’s work.” If it was tradition to repeat episodes of fall shows in the summer, it was also tradition for the writers of those episodes to receive residual compensation. The increase in new shows during the summer, particularly on the big four broadcast networks (ABC, CBS, Fox, and NBC), means fewer opportunities for fall shows to rerun—and that means fewer opportunities for writers to earn residuals.

“In the past, you worked on, say, ER or you wrote L.A. Law and you knew that your show would be on and then air again in the summer and you’d get your residual,” Neal Baer, who is executive producer for the upcoming CBS drama Under the Dome and used to work as a staff writer and producer on shows like ER and Law & Order: Special Victims Unit, told The Daily Beast. “You knew what your income would be because the residual would be part of the income you counted on. Now, there are few shows that generate a lot of residuals.”

Writers often contact the WGA to find out what kinds of residuals they can expect from a TV series they are working on, and often end up banking on the compensation as part of their income—something the WGA says it always cautions against because it can change so wildly. But when a show does repeat—not just during the summer, but at any time of the year, here’s how it typically works:

The credited writer of an episode (whose name follows “written by” or “story by” in the credits) is entitled to residual compensation when it re-airs. There are two ways residuals are calculated: revenue-based, a formula that compensates the writer with a percentage of the money the company earns by showing the episode, and fixed-based, which is a set amount the writer will receive each time the episode is shown. Typically, summer repeats earn writers fixed-based residuals. Imagine how lucrative that would have been for, say, a writer on Friends in the late ’90s when NBC was so keen on summer reruns that it even ran a campaign with the tagline, “If you haven’t seen it, it’s new to you,” promoting its slate of summer repeats to viewers.

Sure, repeats still make up a large portion of each network’s schedule this summer. But the increase in new series—whether it’s Under the Dome on CBS, Mistresses on ABC, or Camp on NBC—means that reruns are being significantly scaled back. “You can imagine that if you’re airing shows in the summer, that you are replacing fall and spring series that are now not getting the same number of repeats in the past,” Baer says.

This summer, NBC has eight shows premiering original episodes. Just three years ago, the network had only four. That’s twice as many series taking time slots that, it’s fairly safe to say, would probably have been occupied by repeats.

But while networks are filling the summer with new shows instead of reruns, there are other outlets from which writers receive residuals. New media certainly brings with it new opportunities for residual compensation. When an episode of a show is posted on a streaming website like Hulu, writers get a fixed-payment residual, as long as it’s within a year after the episode aired. If an episode of an hourlong drama is streaming on Hulu, the writer will receive $800 for the first 26 weeks it’s available. (A 30-minute episode earns the writer $400.) If a streaming website, in this case, Hulu, decides to keep the episode available past those 26 weeks, the writer earns a flat $800. After that first year, compensation then moves to a revenue-based formula. When an episode of a show is made available for permanent download from a site like iTunes, the writer will earn a percentage based on the number of units sold.

This hardly amounts to chump change, but it does amount to drastically less money than writers would earn if an episode they wrote is rerun in the summer, which could, according to this WGA guide, earn a writer thousands of dollars (PDF).

The situation is “changing writers’ earnings and our instincts, too,” Baer says. “Now we have to look to new models for revenues for writers. We have to look for ways to protect writers, especially new ones who aren’t going to get the same residual income we traditionally got.”